1. Field of the Invention
The invention relates to a method of stabilizing siloxanes.
2. Background Art
U.S. Pat. No. 5,569,688 describes the addition of ammonia or an ammonia-releasing compound to addition-crosslinking silicone compositions which contain platinum catalysts and siloxanes having alkenyl groups in order to reduce compression set without adversely affecting crosslinkability.
US 2007/0066783 A1 (DE 10 2005 045 336 A1) discloses the addition of ammonia or an ammonia-releasing compound to addition-crosslinking silicone compositions which contain pyrogenic, hydrophobic silica and SiH crosslinkers in order to improve storage stability; here, storage stability means a largely constant flowability and viscosity of the silicone compositions.
In US 2005/0137362 A1 (EP 1 544 252 A1), organic amines are added to resin-like organopolysiloxanes containing hydroxy groups and also residual amounts of Si-bonded chlorine atoms, in order to increase the storage stability, in particular to avoid viscosity increases through to gelling. The residual amounts of Si-bonded chlorine atoms are disadvantageous since they can lead, e.g. with silanol groups Si—OH, atmospheric moisture, or residual traces of water and alcohol, to generation of hydrogen chloride during storage, and this hydrogen chloride can act as condensation catalyst and lead to viscosity increases through to gelling of the resin-like organopolysiloxanes. The compounds containing amino groups contain 1, 2 or 3 organic radicals on the amino group and are used in large amounts, for example in amounts of 100 ppm by weight.
DE 10 2011 079 751 A1 describes the removal of cyclic siloxanes from short-chain siloxanes having terminal hydroxy groups with the aid of a stream of steam. However, the siloxanes obtained are not storage-stable over a prolonged period of time since the Si-bonded hydroxy groups Si—OH are unstable and form Si—O—Si siloxane bonds by self-condensation with elimination of water. This lack of stability results in the formation of water, clouding, ring formation, and lengthening of the chain, which are disadvantageous.